fix: 백오피스 기능 오류 해결

build.gradle

@@ -202,6 +202,7 @@ project(":layer-admin") {
 
     dependencies {
         implementation project(path: ':layer-event')
+        implementation project(path: ':layer-domain')
 
         compileOnly 'org.springframework.boot:spring-boot-starter-data-jpa'
         compileOnly 'org.springframework.boot:spring-boot-starter-web'

layer-admin/src/main/java/org/layer/admin/retrospect/service/AdminRetrospectService.java

@@ -37,6 +37,12 @@
 import org.layer.admin.retrospect.repository.dto.RetrospectAnswerCompletionDto;
 import org.layer.admin.retrospect.repository.dto.SpaceRetrospectCountDto;
 import org.layer.admin.space.repository.AdminSpaceRepository;
+import org.layer.domain.retrospect.entity.Retrospect;
+import org.layer.domain.retrospect.entity.RetrospectStatus;
+import org.layer.domain.retrospect.repository.RetrospectRepository;
+import org.layer.domain.space.entity.MemberSpaceRelation;
+import org.layer.domain.space.entity.Team;
+import org.layer.domain.space.repository.MemberSpaceRelationRepository;
 import org.layer.event.retrospect.ClickRetrospectEvent;
 import org.layer.event.retrospect.CreateRetrospectEvent;
 import org.layer.event.retrospect.AnswerRetrospectEndEvent;
@@ -58,6 +64,8 @@ public class AdminRetrospectService {
 	private final AdminRetrospectClickRepository adminRetrospectClickRepository;
 	private final AdminMemberRepository adminMemberRepository;
 	private final AdminSpaceRepository adminSpaceRepository;
+	private final RetrospectRepository retrospectRepository;
+	private final MemberSpaceRelationRepository memberSpaceRelationRepository;
 
 	public MeaningfulRetrospectMemberResponse getAllMeaningfulRetrospect(
 		LocalDateTime startTime, LocalDateTime endTime, int retrospectLength, int retrospectCount) {
@@ -203,13 +211,60 @@ public RetrospectCompletionRateResponse getRetrospectCompletionRate(LocalDateTim
 		List<RetrospectAnswerCompletionDto> answerHistories = adminRetrospectAnswerRepository.findRetrospectAnswerCompletionStatsBetween(
 			startTime, endTime);
 
-		// 회고별 완수율 계산 (단위: %)
+		if (answerHistories.isEmpty()) {
+			return new RetrospectCompletionRateResponse(0.0);
+		}
+
+		// 필요한 회고/스페이스/팀 정보를 미리 한 번에 로딩해서 N+1 방지
+		List<Long> retrospectIds = answerHistories.stream()
+			.map(RetrospectAnswerCompletionDto::retrospectId)
+			.distinct()
+			.toList();
+
+		List<Retrospect> retrospects = retrospectRepository.findAllById(retrospectIds);
+		Map<Long, Retrospect> retrospectMap = retrospects.stream()
+			.collect(Collectors.toMap(Retrospect::getId, r -> r));
+
+		List<Long> spaceIds = retrospects.stream()
+			.map(Retrospect::getSpaceId)
+			.distinct()
+			.toList();
+
+		List<MemberSpaceRelation> allRelations = memberSpaceRelationRepository.findAllBySpaceIdIn(spaceIds);
+		Map<Long, Team> teamBySpaceId = allRelations.stream()
+			.collect(Collectors.groupingBy(
+				relation -> relation.getSpace().getId(),
+				Collectors.collectingAndThen(Collectors.toList(), Team::new)
+			));
+
+		// 회고별 분모를 도메인 로직(Team, RetrospectStatus, deadline) 기반으로 계산
 		List<Double> completionRates = answerHistories.stream()
-			.filter(dto -> dto.targetAnswerCount() > 0) // division by zero 방지
-			.map(dto -> (double) dto.actualAnswerCount() / dto.targetAnswerCount() * 100.0)
+			.map(dto -> {
+				Retrospect retrospect = retrospectMap.get(dto.retrospectId());
+				if (retrospect == null) {
+					return null;
+				}
+
+				Team team = teamBySpaceId.get(retrospect.getSpaceId());
+				if (team == null) {
+					return null;
+				}
+
+				long totalCount = team.getTeamMemberCount();
+				if (retrospect.getRetrospectStatus().equals(RetrospectStatus.DONE)) {
+					// 회고가 종료된 경우, deadline 시점의 팀원 수를 분모로 사용
+					totalCount = team.getTeamMemberCountBefore(retrospect.getDeadline());
+				}
+
+				if (totalCount == 0) {
+					return null; // division by zero 방지
+				}
+
+				return (double) dto.actualAnswerCount() / totalCount * 100.0;
+			})
+			.filter(Objects::nonNull)
 			.toList();
 
-		// 평균 완수율 계산
 		double averageCompletionRate = completionRates.isEmpty()
 			? 0.0
 			: completionRates.stream()

layer-api/src/main/java/org/layer/domain/retrospect/service/RetrospectService.java

@@ -135,14 +135,16 @@ public RetrospectListGetResponse getRetrospects(Long spaceId, Long memberId) {
 
 		List<RetrospectGetResponse> retrospectDtos = retrospects.stream()
 			.map(r -> {
-				long writeCount = team.getTeamMemberCount();
+				long totalCount = team.getTeamMemberCount();
 				if (r.getRetrospectStatus().equals(RetrospectStatus.DONE)) {
-					writeCount = answers.getWriteCount(r.getId());
+					// 회고가 종료된 경우, 해당 회고의 deadline 시점의 팀원 수를 totalCount로 설정한다.
+					// RetrospectStatus 가 DONE 으로 변경되면, deadline이 null 값이 될 수 없기 때문이다.
+					totalCount = team.getTeamMemberCountBefore(r.getDeadline());
 				}
 
 				return RetrospectGetResponse.of(r.getSpaceId(), r.getId(), r.getTitle(), r.getIntroduction(),
 					answers.getWriteStatus(memberId, r.getId()), r.getRetrospectStatus(), r.getAnalysisStatus(),
-					answers.getWriteCount(r.getId()), writeCount, r.getCreatedAt(), r.getDeadline());
+					answers.getWriteCount(r.getId()), totalCount, r.getCreatedAt(), r.getDeadline());
 			})
 			.toList();
 

layer-domain/src/main/java/org/layer/domain/space/entity/Team.java

@@ -2,6 +2,7 @@
 
 import static org.layer.global.exception.MemberSpaceRelationExceptionType.*;
 
+import java.time.LocalDateTime;
 import java.util.List;
 
 import org.layer.domain.space.exception.MemberSpaceRelationException;
@@ -30,4 +31,10 @@ public List<Long> getMemberIds(){
 			.map(MemberSpaceRelation::getMemberId)
 			.toList();
 	}
+
+	public long getTeamMemberCountBefore(LocalDateTime end) {
+		return memberSpaceRelations.stream()
+			.filter(memberSpaceRelation -> memberSpaceRelation.getCreatedAt().isBefore(end))
+			.count();
+	}
 }

layer-domain/src/main/java/org/layer/domain/space/repository/MemberSpaceRelationRepository.java

@@ -19,6 +19,9 @@ public interface MemberSpaceRelationRepository extends JpaRepository<MemberSpace
 
     List<MemberSpaceRelation> findAllBySpaceId(Long spaceId);
 
+    @Query("SELECT m FROM MemberSpaceRelation m WHERE m.space.id IN :spaceIds")
+    List<MemberSpaceRelation> findAllBySpaceIdIn(@Param("spaceIds") List<Long> spaceIds);
+
     @Query("SELECT new org.layer.domain.retrospect.dto.SpaceMemberCount(m.space.id, COUNT(m)) " +
             "FROM MemberSpaceRelation m " +
             "WHERE m.space.id IN :spaceIds " +